A new test method for determining water vapor transport properties of polymer membranes

2007 ◽  
Vol 26 (5) ◽  
pp. 685-691 ◽  
Author(s):  
Jianhua Huang
Keyword(s):  
Water Vapor ◽  
Transport Properties ◽  
Polymer Membranes ◽  
Test Method ◽  
Vapor Transport ◽  
Water Vapor Transport

Effect of temperature on water vapor transport properties

2014 ◽  
Vol 38 (2) ◽  
pp. 156-169 ◽  
Author(s):  
Jan Fořt ◽  
Zbyšek Pavlík ◽  
Jaromír Žumár ◽  
Milena Pavlíková ◽  
Robert Černý
Keyword(s):  
Water Vapor ◽  
Transport Properties ◽  
Vapor Transport ◽  
Water Vapor Transport ◽  
Effect Of Temperature

Heat and Water Vapor Transport Properties of Sandwich Composite with Aerogel Insulation

2015 ◽  
Vol 1126 ◽  
pp. 143-147
Author(s):  
Jaroslav Pokorný ◽  
Milena Pavlíková ◽  
Jaromír Žumár ◽  
Anton Trník ◽  
Zbyšek Pavlík
Keyword(s):  
Water Vapor ◽  
Transport Properties ◽  
Thermal Insulation ◽  
Vapor Transport ◽  
Water Vapor Transport ◽  
Sandwich Composite ◽  
Transport Parameters ◽  
Interior Space ◽  
Insulation Systems ◽  
Natural Solution

Several thermal insulation systems were developed for improvement of thermal performance of buildings. Exterior thermal insulation systems represent usually natural solution of the problem of low thermal resistance of building envelopes. However, in some cases, there is necessary to realize interior thermal insulation systems, what brings number of possible problems. Their common disadvantage is a limitation of interior space due to the thickness of thermal insulation layer and a possible condensation of water vapor which permeates the thermal insulation system. On this account, new sandwich composite with silica aerogel originally designed for application in interior thermal insulation systems is studied in the paper. Thermal properties are measured by two transient methods using devices ISOMET 2114 and RTB. The water vapor transport parameters are determined on the basis of dry cup and wet cup methods. The obtained data gives information on thermal and water vapor transport properties of the particular layers of sandwich composite and predetermines its behavior at real climatic exposure of building.

Free volume and water vapor transport properties of temperature-sensitive polyurethanes

2005 ◽  
Vol 43 (14) ◽  
pp. 1865-1872 ◽  
Author(s):  
X. M. Ding ◽  
J. L. Hu ◽  
X. M. Tao ◽  
Z. F. Wang ◽  
B. Wang
Keyword(s):  
Water Vapor ◽  
Transport Properties ◽  
Free Volume ◽  
Vapor Transport ◽  
Water Vapor Transport ◽  
Temperature Sensitive

WATER VAPOR TRANSPORT IN PLASTERS CONTAINING SUPERABSORBENT POLYMERS

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Jan Fořt ◽  
Martin Mildner ◽  
Petr Hotěk ◽  
Robert Černý
Keyword(s):  
Water Vapor ◽  
Relative Humidity ◽  
Transport Properties ◽  
Building Design ◽  
Vapor Transport ◽  
Water Vapor Transport ◽  
Diffusion Resistance ◽  
Vapor Diffusion ◽  
Water Vapor Diffusion

A proper characterization of material properties represents an important step towards an efficient building design. Considering the present issues in the construction sector, moisture loads pose a risk not only to increased material deterioration but also to the health of building inhabitants. In this paper, modified plaster mixtures with superabsorbent admixture are designed in order to improve passive moderation of finishing layers against varying humidity conditions. The relationship between the amount of applied superabsorbent admixture and resulting water vapor transport properties is identified and the influence of temperature on water vapor transport is analyzed. The steady-state cup method is used for the determination of water vapor transport properties, namely the water vapor diffusion permeability, water vapor diffusion coefficient and water vapor diffusion resistance factor. The obtained data show temperature as a very significant factor affecting water vapor transport in the analyzed plasters. Considering the dry-cup method arrangement, relative humidity probes should be used for monitoring relative humidity under the sealed sample for a sufficiently precise determination of water vapor pressure gradient.

Impact of Interstitial Mass Transport Resistance on Water Vapor Diffusion Through Fabric Layers

2012 ◽  
Vol 4 (4) ◽  
Author(s):  
Anshul Sharma ◽  
Sandra K. S. Boetcher ◽  
Walid A. Aissa ◽  
Matthew J. Traum
Keyword(s):  
Water Vapor ◽  
Mass Transport ◽  
Single Layer ◽  
Standard Test ◽  
Test Method ◽  
Vapor Transport ◽  
Water Vapor Transport ◽  
Evaporative Resistance ◽  
Experimental Apparatus ◽  
Significant Magnitude

Textiles maintain wearer comfort by allowing evaporated sweat to permeate through, providing thermal management and keeping skin dry. For single layers, resistance to mass transport is relatively straightforward. However, when textiles are layered, water vapor transport becomes more complex because diffusing molecules must traverse interstitial spaces between layers. Interstitial mass transport resistances of significant magnitude can reduce rates of water vapor transport through layered textile stacks. The prevailing textile mass transport resistance interrogation method is ASTM F1868: “Standard Test Method for Thermal and Evaporative Resistance of Clothing Materials Using a Sweating Hot Plate.” Four improvements to ASTM F1868 are recommended: (1) gravimetric mass transport measurement, (2) evaluating transport using the Stefan flow model, (3) correct accounting for apparatus mass transport resistances, and (4) recognizing and measuring interstitial mass transport resistances. These improvements were implemented and evaluated by running tests using Southern Mills Defender™ 750 fabric, the calibration standard used for ASTM F1868, on a new gravimetric experimental apparatus. For a single layer of calibration fabric, the gravimetric approach is consistent with the prescribed result from ASTM F1868; however, for stacks of two or more calibration fabric layers, the gravimetric approach does not agree with the prescribed ASTM F1868 result due to interstitial mass transport resistance between fabric layers.

Application of genetic algorithm for determination of water vapor diffusion parameters of building materials

2011 ◽  
Vol 35 (3) ◽  
pp. 238-250 ◽  
Author(s):  
Jan Kočí ◽  
Jaromír Žumár ◽  
Zbyšek Pavlík ◽  
Robert Černý
Keyword(s):  
Genetic Algorithm ◽  
Water Vapor ◽  
Transport Properties ◽  
Building Materials ◽  
Vapor Transport ◽  
Water Vapor Transport ◽  
Computational Technique ◽  
Diffusion Parameters ◽  
Materials Research

A combined experimental/computational technique for determination of water vapor transport properties of porous building materials based on the application of genetic algorithm is developed and tested on cellular concrete. The method allows obtaining water vapor transport properties in dependence on relative humidity which is a crucial factor for advanced computational modeling of hygrothermal performance of multi-layered systems of building materials. Moreover, in a comparison with the standard steady-state cup method, the presented technique requires less than half of the time necessary for measurement which, makes good prerequisites for its wider application in materials research.

Thermal and water vapor transport properties of selected lofty nonwoven products

2016 ◽  
Vol 87 (12) ◽  
pp. 1413-1424 ◽  
Author(s):  
Geoffrey RS Naylor ◽  
Cheryl A Wilson ◽  
Raechel M Laing
Keyword(s):  
Heat Flux ◽  
Water Vapor ◽  
Relative Humidity ◽  
Thermal Resistance ◽  
Transport Properties ◽  
Fiber Type ◽  
Vapor Transport ◽  
Water Vapor Transport ◽  
Transient Effects ◽  
Water Vapor Absorption

The mechanism of dry heat flow through lofty nonwoven structures (i.e. thermal resistance) as occurs in quilts has been established. By contrast, there is a scarcity of published information on the water vapor transport properties. This work explores the thermal and water vapor transport properties of a number of different quilt samples with a focus on identifying fiber type effects. Both commercial product and matched laboratory samples were examined. Steady-state thermal resistance and water vapor resistance measurements confirmed that both properties are primarily determined by sample thickness and are largely independent of fiber type. Experiments were also undertaken to observe transient effects. Test samples were initially equilibrated on a ‘dry’ guarded hotplate (35 ± 0.1℃) in a low relative humidity environment (45%). The relative humidity was then rapidly increased to 85%. Compared to polyester, wool samples exhibited a large reduction in the heat flux required to maintain the hotplate temperature. This transient peak lasted for in excess of 1000 seconds. The magnitude of this transient peak in heat flux was proportional to the quantity of wool in the sample and is believed to be associated with the known exothermic nature of water vapor absorption by wool as relative humidity increases. Based on the published values of the heat of water absorption of wool it is estimated that this additional transient heat source is significant relative to a typical human resting metabolic rate and so the effect may be of practical relevance in the bedding environment.

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